Twelve weeks is a good chunk of time — long enough to see real change, short enough to stay committed to. The reason most 12-week plans off the internet fail isn't the exercises, it's that they're a flat list of workouts with no progression built in: same weights, same reps, week after week. Your body adapts in a fortnight and then you're just maintaining.
A 12-week plan that works has progression and a bit of structure baked in — building load over the weeks, and ideally a lighter deload before you're running on empty. This builder structures the twelve weeks around your goal and experience and tracks each session, so week 12 is meaningfully harder than week 1 (which is the whole point). Just try it and see the plan it lays out.